Supporting structure for a washing machine



F. BAUER surroawme smauc'runn FOR A WASHING MACHINE Filed Sept. 29, 19s? May 5, 1970 2 Sheets-Sheet 1 FlG.1

ATTORNEY May 5, 1970 F. BAUER 3,509,742

SUPPORTING STRUCTURE FOR A WASHING MACHINE Filed Sept. 29, 1967 2 Sheets-Sheet z qiaj/ INVENTOR Fritz Bauer" BY ATTORN;

United States Patent Ofice 3,509,742 Patented May 5, 1970 3,509,742 SUPPORTING STRUCTURE FOR A WASHING MACHINE Fritz Bauer, Schulzstrasse 14, Altdorf, near Nuremberg, Germany Filed Sept. 29, 1967, Ser. No. 671,785 Claims priority, application Germany, Oct. 5, 1966, S 106,369; Apr. 29, 1967, S 109,678 Int. Cl. D06f 23/02; F16f /00 US. Cl. 68-231 14 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a resilient supporting structure for a free-oscillating washing machine which is provided with a high speed spinning gear.

The development from the simple drum washer with a horizontal axis to a modern washing machine with a high-speed spinning gear was accompanied by the new problem of providing the machine unit with resilient means for taking up the oscillations which are caused by the inertia due to an unequal mass distribution and which are especially strong when during its acceleration and deceleration the machine passes through the critical speed range. The forces of these oscillations are then transmitted from the machine unit to its supporting base in the form of a plate or frame. It was soon found, however, that such an oscillating machine cannot be rigidly mounted but absolutely requires resilient means for supporting it on its base.

These resilient means which were then developed were of three different types. The "first type consisted of different structures for suspending the washing machine unit by springs from a suitable frame. Although such suspension means are very suitable for taking up the oscillations since they permit the machine unit to swing freely and to carry out its natural oscillating motions, they are not very desirable since they require a very heavy and expensive frame of a considerable height. Because of this height, the oscillation forces are also transmitted to the base by a very long lever arm.

The next development consisted in resiliently supporting the machine unit on compression springs in place of suspending it on tension springs. The motion of compression springs is, however, not a definite motion in only one direction since such springs will not only be compressed in their axial directions but will also yield in transverse directions if transverse forces occur. These supporting means have therefore been supplemented by guiding the spring supports so as to be movable only in a straight direction or by providing additional link connections which are pivotably connected to the machine unit and to the supporting base and thus prescribe the manner and extent of the deformation of the compression springs. Such supporting means, however, restrain the oscillating system to a predetermined oscillating path or circuit and the oscillating motion therefore no longer occurs freely but proceeds in a prescribed manner. Forced or constrained oscillations, however, always cause interfering reaction forces.

The third and so far the best solution of resi iently supporting the oscillating system of a washing machine consists in supporting it only by means of at least three spring legs on the base plate or base frame. The system is then no longer restrained but may swing freely. The importance of this may best be seen by oscillation diagrams which show that the oscillating path is no longer circular but substantially elliptical. It is of extreme importance that the oscillating system will be capable of carrying out such an elliptical motion and will not be restrained by additional connecting links to a circular path.

In order to control the amplitudes of the occurring oscillations and to maintain them within certain limits, it is conventional to provide vibration damping means in the form of mechanical, hydraulic or pneumatic vibration dampers in addition to the supporting springs. Such vibration dampers are therefore also usually provided in connection with a resilient support by means of spring legs.

Although this last supporting system seemed to be the best possible for supporting a washing machine unit, the present inventor, believing that a still better solution could be formed, carried out extensive theoretical calculations and experiments which led to a new construction which at first glance might seem to be practically impossible, namely, a resilient support by means of only two spring legs. However, it was found that this construction is entirely possible and very advantageous provided the two spring legs are equipped with resilient resetting means which during the oscillating movements of the machine unit tend to return them transversely to their original positions so that the machine unit cannot turn over toward one side or the other but if it starts to tilt over a force will become effective which tends to erect the machine unit and return it to its horizontal position.

The two spring legs should, however, not be connected at any arbitrary points to the machine housing but in positions which are located substantially within the plane of the center of gravity of the machine unit, hereafter simply called the gravity plane. The points of connection do not have to be located exactly Within this plane but may be located at a short distance before or behind it, as seen in the axial direction of the machine housing, provided this distance is not made so large as to render the system unstable. The most suitable position on the machine housing to which the spring legs are to be connected may be easily determined by a simple test on each first model or prototype of a washing machine of this kind.

Aside from the mentioned resetting means and the connection of the spring legs substantially within the gravity plane of the machine unit the supporting structuxe according to the invention has to have an additional feature which consists in mounting the spring legs at an oblique angle to the perpendicular plane so that the extensions of their axes intersect within the gravity plane.

The resilient supporting structure according to the invention has the great advantage over all other suspension and supporting structures which have previously been developed especially for washing machines with high-speed spinning gears that it not only is of a much greater simplicity of construction, one which can hardly be surpassed, but especially that it results in a quietness and steadiness of operation of the machine which is even considerably better than that of a machine which is freely oscillating by being supported on at lea-st three spring legs.

In order to ascertain the manner in which the oscillating washing machine unit which is supported in accordance with the invention will behave under aggreviated operating conditions, an additional weight which at first was placed within the gravity plane was once shifted to the vicinity of the inlet opening in one end of the drum and thereafter to the vicinity of the other end of the drum'. Thus, operating conditions were simulated which in this excessive form will never occur in the actual operation of such machines. It was found, however, that despite these excessive dynamic imbalances the oscillations were so completely taken up by the new supporting structure that only a very light trembling could be felt on the base of the machine.

Another interesting observation was made in the numerous tests, namely, that the compression springs of the two spring legs according to the invention need not be stronger than those required when four spring legs are provided.

As in other resilient supporting structures, it may be advisable and in certain cases even necessary also to provide the two-leg support according to the invention with vibration damping means. It has, however, been found that a single vibration damper will generally be sufficient and that it is immaterial whether it is of a mechanical, hydraulic or pneumatic type.

It has further been found that the location and arrangement of the vibration damper relative to the machine unit is of considerable importance. Since contrary to a three or four-leg support as previously employed only two spring legs participate in each oscillating movement of the machine unit, the oscillating system is relatively yielding within the plane of the two spring legs so that the oscillation ellipse has a relatively long axis. Accord in-g'to the invention it is therefore advisable to mount the vibration damper and connect it to the machine unit at such an angle that its maximum damping effect will extend in the direction of the long axis of oscillations. Although the vibration damper could be built directly into at least one of the spring legs, it is more advisable for the reasons as already stated to provide it as a separate component which is mounted at an angle as prescribed above. This, however, does not exclude the possibility of providing an additional vibration damper within at least one of the spring legs, preferably in the form of a friction damper which may be easily installed therein and will then result in an increased damping of the oscillations.

It has already been mentioned that the two spring legs must be provided with a resetting, erecting or centering force; The most simple and inexpensive manner of producing such a resetting force consists in the provision of a rubber block on one end or still better on both mounted ends of each spring leg. Assuming that each spring leg is pivotably mounted on the machine housing by means of a-ball-and-socket connection and is connected to the machine base by one or two rubber blocks, and that the machine unit will then swing toward one side within the plane of the spring legs, that is, within the gravity plane of the machine unit, the rubber blocks will then be compressed and tend to return the stored energy as a resetting force. 'This resetting force is, of course, increased if both ends of each spring leg are clamped in rubber blocks. Although, this manner of mounting is not new as such, it is of particular importance in connection with the two-leg support according to the invention.

In place of such rubber blocks it is also possible although more expensive to provide additional centering springs for example, in the form of leaf springs, which may be relatively soft and act directly upon the machine housing within the plane of oscillation, while their lower ends are secured to the machine base. However, such centering springs are not only more expensive but they also do not seem to have any particular advantage over the use of rubber blocks for mounting the spring legs.

The ends of the spring legs should preferably be mounted in such a manner that each spring leg can also carry out a kind of wobbling motion which under certain operating conditions may be caused by an imbalance of the machine unit. The same applies to the mann r o mounting the vibration damper. This can best be accomplished by clamping these parts between rubber blocks. The machine unit should therefore also have a certain resilience n the axial direction of its drum since a rigid mounting in this direction may easily lead to excessive stresses.

For the manner of mounting the vibration damper in connection with the spring legs according to the invention the following considerations are of importance.

The oscillating system is composed of the washer drum which revolves at a high speed, the housing containing this drum, and the driving motor, the transmission gear, and other parts which are mounted on this housing For this system a gravity plane may be determined within which or closely adjacent to which the spring legs should be located. The laundry within the drum forms an eccentric mass. If the washing machine is constructed so that this eccentric mass will likewise be located within the gravity plane, the axis of the drum will move during each oscillation substantially parallel to its normal position along a circle or an ellipse. This applies substantially to a machine which is filled through an opening in its peripheral wall. In such a machine, the vibration damper would therefore have to be mounted within or closely adjacent to the gravity plane. If the washing machine is to be filled through an opening in one of its end walls, it will be more likely that the laundry will be accumulated in the vicinity of this end wall and that the eccentric weight will be displaced from the gravity plane toward the front. The axis of the machine unit will then not carry out a movement parallel to its normal position but a conical movement. In such a case it will therefore be necessary also to mount the vibration damper in front of the gravity plane since it then has not only the purpose to take up the actual oscillations of the machine but the conical movement as well. The opposite conditions apply if the machine is designed so that an accumulation of the laundry may be expected behind the gravity plane. The vibration damper would then have to be connected to the machine housing behind the gravity plane.

Since the machine unit which is supported by two spring legs is not supported in the direction of the drum axis, that is, transversely to the plane of the spring legs, it might be able to oscillate in this direction around the lower connecting points of the spring legs. It could pivot, for example, in the direction toward the rear wall of the housing when the laundry is filled into the drum. This would generally not be a serious disadvantage since a buffer could be provided on the rear wall of the housing on which the drum may engage. This will, however, also be unnecessary if the ends of the spring legs are clamped between rubber blocks since these blocks may also be deformed in the direction parallel to the axis of the drum and will therefore counteract a swinging of the housing in the axial direction of the drum.

According to a further embodiment of the invention, the oscillating machine unit is supported on at least three points on the machine base by each of two spring legs so as to be freely oscillatable. At least one of these points is connected to the swinging machine unit, while the two other points are spaced from each other in the direction parallel to the axis of the drum and are connected to the machine base.

Assuming this to be a simple three-point support, the upper end of each spring leg is pivotably connected to the machine unit, while its lower end is connected to the machine base but at two points which are laterally spaced from each other in a direction parallel to the axis of the drum and are resiliently connected to the machine base. The particular construction of this connection is of secondary importance, provided the machine unit can still carry out freely its natural oscillating motion. Insofar as the normal oscillations are concerned which extend within a plane at a right angle to the axis of the drum, each of the two spring legs which is mounted at three points acts like one which is connected at only two points. The new effect occurs when the machine unit moves in the direction of the drum axis. Assuming that, when laundry is being inserted into the drum through the opening in one end wall thereof, a force will be exerted upon the edge of the drum opening which will press this opening downwardly so that the drum together with the remainder of the machine unit will tilt forwardly. Although a spring leg which is connected at only two points to the machine housing and the machine base could possibly follow such a tilting movement, its resetting force is so small that it could not prevent the machine unit from being tilted too far and would especially not be able to return the tilted unit to its original position. Entirely different conditions result, however, if the lower end of each spring leg is resiliently mounted at two points which are spaced laterally from each other. If the machine unit then tilts in the same manner as described above, it will produce oppositely directed forces at these two points. At the point which is located more closely to the opening in the end wall of the drum housing the resilient material which connects the lower end of each spring leg to the machine base will be compressed, while at the point which is more remote from this opening the resilient material will expand. The resulting forces therefore have the tendency to reerect the machine unit to its original horizontal position. The machine unit can therefore tilt only to a limited extent and will be returned by a strong force to its normal position. The combined action of the two lower re- :rilient connecting points of each spring leg results in a very effective stabilization of the machine.

Such a three-point support of each spring leg will generally be adequate. In certain cases it may, however, be necessary also to mount the upper end of each spring leg at two points which are spaced from each other in the axial direction of the drum. Since near the point of connection of each spring leg to the machine housing the same kind of forces are produced as at its point of connection to the machine base, the stabilizing effect of the spring legs will be further increased.

The usually most suitable arrangement of the two spring legs relative to the machine unit is the symmetrical arrangement in which the spring legs are located and connected to the machine housing substantially within a central plane of the latter which extends at a right angle to the axis of the drum. This, however, is by no means the only suitable arrangement since there may be cases in which it is more advisable to mount the two spring legs within two different planes which extend parallel to the central plane so that one spring leg is located in front of the central plane, as seen from the inlet side of the drum, while the other spring leg is located behind the central plane. This arrangement may be preferred over the symmetrical arrangement especially when it is to be expected that the laundry will not be distributed substantially equally at both sides of the central plane but be located more toward one end wall or the other so that certain transverse forces will be produced which may result in a wobbling motion of the machine unit. By offsetting the two spring legs relative to the central plane it is possible to counteract such wobbling movements very effectively.

The two lower connecting points of each spring leg may be formed by rubber elements which are clamped by separate bolts between the machine base and the lower end of the spring leg. A more simple and effective construction consists, however, in providing the two connecting points at both sides of the central axis of each spring leg in the form of one continuous elongated rubber block or, according to a modification of the invention, in the form of two superimposed elongated rubber blocks.

The features and advantages of the present invention will become more clearly apparent from the following description thereof which is to be read with reference to the accompanying drawings which illustrate the principles of the invention as being applied to several preferred embodiments thereof and in which:

FIG. 1 shows a side view of a washing machine with a supporting structure according to the invention;

FIG. 2 shows a front view thereof;

FIG. 3 shows a front view of a washing machine similar to that as shown in FIGURE 2 with a supporting structure according to a modification of the invention;

FIG. 4 shows a side view similar to FIG. 1 of a washing machine with a supporting structure according to a further modification of the invention;

FIG. 5 shows an enlarged view of the lower end of a Spring leg according to FIG. 4 and of the resilient supporting means thereof;

FIG. 6 shows, partly in cross section, a further modification of the upper end lower parts of a spring leg and their resilient supporting means, while FIG. 7 shows a perspective view of a modification of a structural detail of the device as shown in FIG. 6.

Referring first to FIGS. 1 to 3 of the drawings, the washing machine as illustrated diagrammatically consists of a machine unit comprising a housing 1 in which a drum (not shown) is rotatably mounted, an electric motor 2 which is mounted on the housing 1, and a V- belt drive 3 for driving the drum within the housing about a normally horizontal axis as indicated by the line 4. This washing machine is of a conventional type wherein the drum is adapted to be filled with laundry when a hinged cover on one end wall of housing 1 is opened. According to the invention, this machine unit is resiliently supported by only two telescopic spring legs 7 and 8 on a base 5 which may consist of a plate or frame and may be provided with adjustable feet 6. As shown particularly in FIG. 1, the two telescopic spring legs 7 and 8 are located within the same vertical plane which is determined by the plane S of the center of gravity of the machine unit 1 to 3 which may be easily ascertained by suspending this unit on a hook and by shifting the point of connection of this hook to the housing 1 until it is in a state of balance and its axis extends horizontally. Of course, this operation needs to be carried out only once on a prototype of the particular machine model since the structural details of the machines which are built thereafter will remain the same. In the washing machine as actually used, the suspension hook is therefore omitted. The spring legs 7 and 8 are therefore located and connected to housing 1 within this plane S or vertically to the horizontal base 5 but are inclined thereto at an angle or so that the extensions 7' and 8' of the axes of these spring legs 7 and 8 intersect at a point P within the plane S above the machine housing 1.

In this particular embodiment of the invention, the resetting force which tends to return the machine unit during its oscillating movement to its normal position in which the central axial plane of housing 1 extends horizontally and at a fixed distance from the base 5 is produced by the resilience of rubber blocks 10 and 11 which connect the opposite ends of spring legs 7 and 8 to the housing 1 and base 5. Thus, the upper ends of spring legs 7 and 8 are mounted on rubber blocks 10 which, in turn, are secured to brackets 12 which are welded to housing 1, while the lower ends of the spring legs are mounted on rubber blocks 11 which, in turn, are connected to brackets 13 on the base 5. Extensive tests have shown that this oscillating system consisting of the machine unit and its supporting means is statically and dynamically stable and thus entirely fulfills the requirements which can be made upon such a structure.

In addition to the telescopic spring legs 7 and 8, the machine unit 1 to 3 is supported by a vibration damper 15 of any suitable type and construction which is pivotably connected to the housing 1 at a point 16 and to the base 5 at the point 14. In this case, no rubber blocks are provided as on the spring legs, but link pins with a rubber lining.

It can be easily seen that the machine unit may yield easily on the general direction of the arrow F since there are no further supporting means except those within the gravity plane. The ellipse of oscillation therefore has a relatively long axes in this general direction. In order to reduce the amplitude of these oscillations as effectively as possible, the vibration damper 15 is connected to the housing 1 and the base 5 so as to be inclined to the latter at an angle 6 which is smaller than the angle a. If the damping force is divided into a horizontal component and a vertical component, it is possible by making the angle I {3 of a suitable size to produce a greater damping effect in the direction of the arrow F than vertically thereto. It would be inadvisable to extend the vibration damper too much in accordance with the long axis of the ellipse since the component which extends vertically thereto and should likewise contribute to the damping action would then be too small.

FIG. 3 illustrates a machine unit similar to that as shown in FIGS. 1 and 2 which, however, is provided with a difierent supporting structure insofar as the spring legs are pivotably connected to the housing 1 and to the base 5 by ball-and-socket joints 17 and 18 and the resilient resetting or centering means are not provided in the form of rubber blocks or the like on the spring legs themselves but in the form of leaf springs 19 and 20 the lower ends of which are secured to the base 5, while their upper ends act upon the opposite sides of housing 1. The vibration damper as shown in FIGS. 1 and 2 has in this case been omitted so as to indicate that the new supporting system is not absolutely dependent upon the presence of a vibration damper, although generally it is advisable and may sometimes even be necessary to provide it.

The further embodiment of the invention as illustrated in FIGS. 4 to 7 is designed according to the same principles as the embodiment according to FIGS. 1 and 2, although. it diifers structurally therefrom by the fact that the lower ends of the spring legs 7 and 8 are supported at two points A and B which are spaced at a distance a from each other, as indicated in FIG. 4, only diagrammatically by dotted lines. If connecting lines are drawn between the points A and B and the clamped upper end of each spring leg, a triangle is formed. The machine unit is therefore no longer supported merely on straight legs at two points but so-tospeak on triangular supports and can therefore tilt only if its center of gravity swings beyond one of the points A or B which can occur only under unusual operating conditions. As long as during the oscillatory movements of the machine unit its center of gravity does not swing beyond one of the points A or B, it will after each of these movements be automatically returned to its original central position.

The lower end of each spring leg 7 and 8 must be connected to the base 5 so as to permit the machine unit to oscillate freely. According to one embodiment of the in vention as illustrated in FIG. 5 which only shows the lower end of the spring leg 7, the two points of connection of the lower end of each spring leg to the base 5 are formed by two pairs of rubber bushes 26, 27 and 2-8, 29 which are inserted between a plate 30 which is secured to the part 31 of the spring leg by a nut 36, a plate 32 on the bracket 13 which is secured to the base 5, and a further plate 33 and are clamped together with these plates by bolts and nuts 34 and 35. If the spring leg 7 and thus also the part 31 thereof swings in the counterclockwise direction, the rubber bushes 26 and 29 will be compressed and therefore exert a reactive force in the clockwise direction upon the spring leg which tends to return the latter to its original position and thus the machine unit to its central position.

The device according to FIG. 5 therefore forms a threepoint support of the oscillating machine unit by each of two spring legs. FIG. 6 illustrates a further improvement of this supporting device which consists in replacing the three screwed connections 34, 35, and 36 by a single nut 37 which is screwed upon the threaded end 38 of the part 31 of the spring leg, and in replacing the separate rubber bushes 26, 28 and 27, 29 by two elongated rubber blocks 39 and 40 which are of a substantially rectangular shape and extend substantially parallel to the axis of housing 1. The support on two separate surfaces according to FIG. 5 is replaced in FIG. 6 by a support on two surfaces which are located at both sides of the axis of the spring leg. The two supporting structures according to FIG. 5 and FIG. 6 are, however, equal in principle insofar as the lines A and B extend through the centers of the two support points and are spaced at a distance a from each other. The lower end of each spring leg is therefore again mounted so that a triangular support is formed as previously described with reference to FIG. 4. Aside from the simplicity of mounting each spring leg, the device according to FIG. 6 has the special advantage that the relatively large rubber blocks have a greater deformation capacity.

The supporting device according to FIG. 6 is composed of a pair of plates 41 and 42 on the part 31 of the spring leg which clamp the two elongated rubber blocks 38 and 39 together and against the opposite sides of the part 32 of the bracket 13 by means of a nut 37 which is screwed upon the threaded end 38 of the part 31 of the spring leg. Since there is only one screw connection 37, 38 for securing the spring leg including the rubber blocks 39 and 40 to the bracket 13 on the base 5, the device according to FIG. 6 may be more easily assembled than the device according to FIG. 5

The rubber blocks 39 and 40 according to FIG. 6 are further provided with projections 43 which engage into corresponding recesses in the plates 41 and 42 and in the bracket part 32 of the base 5. The different parts are thus nonrotatably connected to each other and therefore cannot shift relative to each other while being assembled.

Another manner of nonrotatably securing these parts to each other is illustrated in FIG. 7. In this case, plate 41 is made of a U-shaped cross section and thus provided with lateral webs 44, while on the part 31 of the spring leg a hexagonal part is secured the opposite surfaces of which are spaced from each other at a distance substantially equal to the distance between the webs 44. When the hexagonal part 45 is inserted between the webs 44 on plate 41, the part 31 of the spring legs is prevented from turning relative to plate 41 and thus also relative to the rubber blocks 39' and 40' and bracket 13 which is rigidly secured to or forms a part of the base 5.

As previously described, although not particularly illustrated in the drawings, it may in certain cases be advisable to mount both spring legs 7 and 8- so as not to extend within the gravity plane S, as shown in FIG. 1, but at a small distance from the opposite sides of this plane so that, for example, the spring leg 7 will be located more toward the front wall and the other spring leg 8 more toward the rear wall of the housing 1.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, I wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the invention.

Having thus fully disclosed my invention, what I claim is:

1. A resilient supporting structure for an unrestrained oscillating washing machine unit comprising a housing, a drum rotatably mounted in said housing and having a normally horizontal axis, and means for driving said drum, said supporting structure comprising a base and only two telescopic spring legs connected at their opposite ends to opposite lateral sides of said housing and to said base and extending closely adjacent and substantially parallel to a vertical plane passing through the center of gravity of said unit and being inclined relative to said leg at least to said base so as to be movable in all directions relative to said base.

3. A supporting structure as defined in claim 2, where in said machine unit is supported by each of said two telescopic spring legs at least at three points relative to said base so as to be unrestrainedly oscillatable, at least one of said points being disposed on the upper end of said spring leg and connecting the same to said housing, and the other two points formed by the connection of at least said one resilient element to the lower end of said telescopic spring leg and to said base, said two other points being spaced from each other in a direction substantially parallel to said axis of said drum.

4. A supporting structure as defined in claim 3, further comprising at least one resilient element connecting the upper end of each telescopic spring leg resiliently at least at said one point to said housing.

5. A supporting structure as defined in claim 3, further comprising a plate secured to the lower end of each telescopic spring leg, said two other points being formed by separate rubber elements located at opposite sides of the central axis of each telescopic spring leg and clamped between said plate and said base and connecting the same to each other.

6. A supporting structure as defined in claim 2, wherein each telescopic spring leg comprises a threaded lower end portion, a plate mounted to said end portion, at a distance from its lower extremity, and resilient means comprising at least one elongated rubber block extending to the opposite sides of the axis of said telescopic spring leg and having a substantially central aperture, said threaded end portion extending through said aperture and through an aperture in a flat part of said base, said threaded end portion further including a nut for clamping said rubber block between said plate and said base.

7. A supporting structure as defined in claim 6 wherein said resilient means comprise a pair of said elongated rubber blocks on the upper and lower sides of said flat base part, said threaded end portion of said telescoping spring leg extending through said apertures in said rubber blocks and in said base part, a second plate on the lower side of said base part, and a nut on said threaded end portion for clamping said rubber blocks between said plates to said base point.

8. A supporting structure as defined in claim 7 wherein at least one of said plates and said flat base part have recesses and said rubber blocks have corresponding projections engaging into said recesses for preventing at least said rubber blocks from turning relative to said base.

9. A supporting structure as defined in claim 7 further comprising a polygonal member secured to said threaded lower end portion, said first plate having wall portions projecting from the upper side thereof, said polygonal member adapted to engage between said wall portions so as to prevent said telescopic spring leg from turning about its axis relative to said base.

10. A supporting structure as defined in claim 2, wherein said two telescopic spring legs are located at both sides of a plane of symmetry extending vertically to said axis of said drum.

11. A supporting structure as defined in claim 1, wherein said resetting means comprise rubber elements clamped to both ends of each of said telescopic spring legs and connected to said housing and to said base.

12. A supporting structure as defined in claim 1, wherein said resetting means comprise leaf springs each secured at one end to said base and at the other end acting upon said housing.

13. A supporting structure as defined in claim 1 further comprising at least one vibrator damper connected to said housing and to said base and having an axis extending at a smaller angle to said base than the axis of each of said telescopic spring legs.

'14. A supporting structure as defined in claim 13, wherein said vibration damper is connected to said housing and said base at points spaced from one side of said vertical plane so as to be located closer to one end wall of said housing.

References Cited UNITED STATES PATENTS 2,579,472 12/ 1951 Cham'berlin et al. 6-824 2,117,919 5/1938 Summers 24821 XR 2,270,335 1/ 1942 Parkinson et al. 248--21 XR 2,585,107 2/1952 Geldhof 24822 2,589,796 3/1952 Geldhof 24822 2,631,810 3/1953 Zuhn 24822 XR 2,642,996 6/1953 Oeler et al 68--24 XR 2,948,401 8/ 1960 Obermajer 248-22 XR 2,975,626 3/1961 Frey 6 824 XR 3,052,435 9/1962 Roller 248--21 XR 3,089,326 5/1963 Belaieff 68-24 3,373,962 3/1968 Blaiklock et al. 24822 XR ROBERT L. BLEUTGE, Primary Examiner US. Cl. X.R. 

